Carbon nanotubes mediating nano α-FeOOH reduction by Shewanella putrefaciens CN32 to enhance tetrabromobisphenol A removal.

Carbon nanotubes (CNTs) mediation of the reduction of nano goethite (α-FeOOH) by Shewanella putrefaciens CN32 to improve the removal efficiency of tetrabromobisphenol A (TBBPA) was investigated in this study. The results showed that CNTs effectively promoted the biological reduction of α-FeOOH by strengthening the electron transfer process between Shewanella putrefaciens CN32 and α-FeOOH. After α-FeOOH was reduced to Fe(II), the adsorbed Fe(II) accounted for approximately 69.07% of the total Fe(II). And the secondary mineral vivianite was formed during the reduction of α-FeOOH, which was determined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The vivianite (Fe(PO)·8HO) was formed by the reaction of PO and Fe(II). The degradation effect of TBBPA was the best at pH 8. CNT-α-FeOOH reduced the toxicity of TBBPA to CN32 and had good stability and reusability. The byproduct bisphenol A was detected which indicated that the degradation pathway of TBBPA involved reductive debromination. Electrochemical experiments and EPR analysis showed that the electron transfer capacities (ETC) of CNTs was an important factor in the removal of TBBPA, and it may greatly depend on semiquinone radicals (CO). This study provided a new method and theoretical support for the removal of TBBPA in the environment.